1. Field of the Invention
The invention relates to a storage-stable preparation that comprises sorbic acid and other acids and can be used alone in feeds or in a mixture with other feed additives in farm animal husbandry.
In the animal feed sector, antibiotics are frequently used as growth promoters. The use of antibiotics in this sector is under suspicion for being responsible for hazards which start from resistant bacteria that can also in the long term endanger human health. Therefore, products which are of less concern for health must be sought for this usage. Thus, in other sectors also, substances which are of concern for health physiologically and epidemiologically, or are harmful for the environment, for example antibiotics, formaldehyde-releasing substances, halogenated substances, and many more, are increasingly being replaced by substances of less concern for example in foods, feeds, pet food, silages, pomace, or other wastes from the food industry. The purpose of these substances, firstly, is directed toward retaining the value of the actual product. Secondly, however, their hygienic state is to be improved, or prolonged shelf-life is to be achieved.
2. Description of the Related Art
It is known that sorbic acid can be used to preserve feeds. Sorbic acid (trans,trans2,4-hexadienoic acid) is a colorless solid compound which dissolves only sparingly in cold water and is used worldwide as a preservative. The principle of action is determined by sorbic acid in undissociated form. The optimum action is therefore exhibited by sorbic acid in the acidic pH range. Sorbic acid and its salts have a very good microbiostatic, antimycotic action. At the same time, sorbic acid, as an unsaturated fatty acid, is virtually nontoxic, which is confirmed by very extensive data, and by the decades-long use of this acid in the food sector, in animal feed etc.
In addition to sorbic acid, other organic acids have been used for years to preserve feeds and to improve feed hygiene. Special requirements may be made of hygienic quality precisely in feed for young animals. Therefore, some organic acids are approved as feed additives, on the basis of national provisions in feedstuff law without limitation of maximum levels.
Previously, feed experiments have been carried out, predominantly with piglets, which verified that various organic acids, such as citric acid, fumaric acid or formic acid are able to affect animal growth in a positive manner if they are admixed to the piglet feed in an optimum dose (Kirchgessner and Roth 1991; Roth and Kirchgessner 1998). Very recently, it has also been shown that sorbic acid at high concentrations (1.8-2.4% sorbic acid, based on the feed) has a high nutritional activity for growing piglets (Kirchgessner et al. 1995).
Individual organic acids are increasingly being used in animal nutrition. Frequently, the liquid state, the volatility of some acids or, however, poor solubility of their sodium, potassium, calcium or magnesium salts is disadvantageous. Frequently, poor miscibility or incompatibility of these acids may be observed. Thus, for example, mixtures of formic acid and benzoic acid exhibit a rapid brown discoloration, which is possibly due to oxidation reactions.
It is known that feeds have a high buffering capacity. In order to overcome this buffering capacity of the feed, acids can be admixed to the feed. In addition, owing to the dependence on the pH, there is the necessity, in feeds having a high buffering capacity, to use high concentrations of some acids which, for example when propionic acid is used, very rapidly make themselves noticeable disadvantageously by their sensory properties. DE-A 197 39 319 describes a solution to this problem. There, salts impregnated with liquid carboxylic acids are described, in particular combinations of preservative acids with corresponding salts. In the case of the impregnated salts described in DE-A 197 39 319, however, the required pH reduction cannot be achieved, since the salts already present buffer the pH (see Example 15 in DE-A 197 39 319: impregnated salt of sodium formate and formic acid: from pH 6.4 to 5.5 and 5.1 at 10 or 20 kg/metric t of feed). In addition, in the case of the impregnated salts described in DE-A 197 39 319, rapid discoloration or liquefaction must be expected. These changes may be observed even after a short time without sufficiently large carrier/stabilizer quantities, so that here virtually no usable product can be obtained. Furthermore, an active compound content of only up to about 75% by weight (calculated as total acid) is achieved.
Overall, a disadvantage of such previously known feed additives, impregnated salts and the feeds produced therewith was that they are relatively unstable and, even after a relatively short storage time, deliquesce, clump or show brown discoloration. In addition, they do not contribute to effective acidification of the feed, and only a little acid can be added per unit weight of the additive. The object was therefore to provide a stable mixture of acids which does not have these disadvantages.
This object is achieved by a preparation (composition), which comprises sorbic acid, at least one organic acid which is liquid at room temperature (=23xc2x0 C.) and at least one other organic acid which is solid at room temperature, which are different from sorbic acid. Preference is given to a preparation which, in addition to said constituents, comprises a carrier.
Surprisingly, the inventive preparations do not have the abovedescribed disadvantages. The preparations rather show an unexpected high stability, combined with good properties in handling. Furthermore, effective acidification of the feed is achieved. In addition, surprisingly, a beneficial effect on growth performance of young animals can be observed, even at relatively small amounts of acid.
The percentages by weight specified below relate to the total mass of the preparation.